Hydocracking and hydrodesulfurization processes utilizing a salt-containing neutralized silica-alumina support calcined at different temperature ranges

ABSTRACT

RESIDUAL OILS CONTAINING AASSPHALTNES, LARGE AMOUNTS OF SULFUR AND/OR HEAVY METALS ARE HYDRODESULFURIZED AND/OR HYDROCRACKED IN A PROCESS WHICH UTILIZES A CATALYST PREPARED BY FIRST NEUTRALIZING A CALCCIINED SILICIA-ALUMINA SUPPORT WITH A NITROGEN BASE, DEPOSITING A HYDROGENATION METAL COMPONENT ON THE SUPPORT BY CONTACTING IT WITH AN ALKALINE SALT SOLUTION OF CATALYTICALLY ACTIVE METALS, THEN CALCINING THE SALT-CONTAINING SUPPORT IN AN OXYGENCONTAINING GAS AT A TEMPERATURE IN THE RANGE OF ABOUT 185-400*C., AND FINALLY CALCINING IN AN OXYGEN-CONTAINING GAS AT A TEMPERATURE IN THE RANGE OF ABOUT 475-650* C. FOR AT LEAST ABOUT 1 HOUR. THE OXYGEN CONTENT OF THE CALCINING GAS AND THE FIRST CALCINING TIME ARE REGULATED TO AVOID SINTERING THE HYDROGENATION METAL COMPONENT.

y 1974 J. VAN KLINKEN E'TAL HYDROCRACKING AND HYDRODESULFURIZATIONPROCESS UTILIZING A SALT*CONTAINING NEUTRALIZED SILICA'ALUMINA SUPPORTCALCINED AT DIFFERENT TEMPERATURE RANGES 2 Sheets-Sheet 1 Original FiledOct. 8. L969 FIG.

E R w G C M I o I i wM E I CT B S 0 U o A 7 N A L I m D R E 0 wk 5 m T LL A m C T I R m m m F F 3 D I\I IV 0 m T T A A O DIFFERENTIAL THERMALANAL YSIS I IOO III A 0 NITROGEN CALCINED FIG.

I May 14, 1,14 VAN KE ETAL 3,810,830

HYDROCRACKING AND HYDRODESULFURIZATION PROCESS UTILIZING ASALT-CONTAINING NEUTRALIZED SILICA-ALUMINA SUPPORT CALCINED AT DIFFERENTTEMPERATURE RANGES Original Filed Oct. 8. 1969 2 Sheets-Sheet 2DIFFERENTIAL THERMAL ANALYSIS 1 l I I I I DIFFERENTIAL TEMPERATURE 0 I00300 500 700 0C CALCINING TEMPERATURE +AT AIR CALCINED FIG. 3

m -AT 5 DIFFERENTIAL THERMAL ANALYSIS 2 0: Lu (L E O I, A I I J 0\ 300500 700 I... E {5 AT E c 6 CALCINING NITROGEN CALCINED TEMPERATURE FIG.4

,Unied. S ates i 3,810,830 z n HYDOCRACKING' AND *HYDRODESULFURIZA- TIONPROCESSES UTILIZING A SALT-CON- TAINING NEUTRALIZED SILICA-ALUMINASUPPORT CALCINED AT DIFFERENT TEM- PERATURE RANGES Jakob van Klinken,Herman wonter Kouwenhoven, and

Pieter Aldert van Weeren, Amsterdam, Netherlands, assignors to Shell OilCompany, New York, N.Y. Originalapplication Oct. 8, 1969, Ser. No.864,707,-now Patent No. 3,697,444, dated Oct. 10, 1972. Divided and thisapplication June 2, 1972, Ser. No. 259,110 Int. Cl. Cg 13/02, 13/06,23/02 US. Cl. 208-111 14 Claims ABSTRACT OF THE DISCLOSURE Residual oilscontaining asphaltenes, large amounts of sulfur and/ or heavy metals arehydrodesulfurized and/or hydrocracked in a process which utilizes acatalyst prepared by first neutralizing a calcinedsilica-alumina supportwith a nitrogen base,.depositing a hydrogenation metal component on thesupport by contacting it with an alkaline salt solution of catalyticallyactive metals, then calcining the salt-containing support inanoxygcncontaining gas at a temperature in the range of about 185-400C., and finally calcining in an oxygen-containing gas at a temperaturein the range of about 475-650" C. for at least about 1 hour. The oxygencontent of the calcining gas and the first calcining time are regulatedto avoid sintering the hydrogenation metal component.

. RELATED APPLICATION This is a division of application 'SerJNo'.864,707,"filed Oct. 8, 1969, now'U.S.' Pat. No. 3,697,444,"issu'ed Oct.10,1972. I

BACKGROUND OF THE INVENTION.

Field ofithe invention The invention relates to a process for thepreparation of a porous, slica-alumina based hydrocarbomconversioncatalyst. It also relates to hydrocarbon-conversion processes in whcihthese catalysts are applied, in particular to the catalyticdesulfurization of hydrocarbon residues.

Discussion of the prior art In the oil-processing industrya large numberof hydrocarbon-conversion processes are applied in which thehydrocarbons or hydrocarbon oils to be converted are contacted withhydrogen in the presence of a catalyst. As a rule, such processes can begrouped under the general heading catalytic hydrotreating. Catalytichydrotreating is generally applied for improving the quality ofhydrocarbon oil or for converting heavier hydrocarbon oils derived frompetroleum into lighter and more desirable petroleum products. Theseproducts may be the feedstock for other catalytic conversion processesor may be applied in the petrochemical industry. During catalytichydrotreating not only a large part of the sulfur and nitrogenoriginally present in petroleum fractions is removed from thehydrocarbon fraction treated, but at the same time the hydrocarbon feedis wholly or partially cracked and converted intolower-molecular'hydrocfibons. Depending on the primary objective,catalytic. hydrotreating called hydrodesulfurization or hydrocracking.

' pounds. Moreover, a deasphaltenizing process leads to 3,810,830Patented May 14, 1974 Hydrocracking is the general term for conversionprocesses in which destructive hydrogenation takes place and in whichhydrocarbon feed of relatively high molecular weight are converted intolower-molecular compounds at relatively high temperature and pressure.In such processes sulfur and nitrogen-containing compounds are alsoconverted,' with formation of hydrogen sulfide and ammonia, whileunsaturated compounds originally present in the petroleum or formed incracking are converted into saturated compounds.

For the catalytic hydrotreating of petroleum fractions a large number ofcatalysts have been developed, which specifically, either promote thedesulfurization reaction or the hydrocracking reaction. Such catalystsmay be based on refractory amorphous carriers consisting of inorganicmetal oxides or mixtures of metal oxides, or on crystalline carriers,such as the now frequently applied aluminosilicates or molecular sieves.Such carriers are generally combined with catalytically active metalsfrom Group VI-B and/or Group VIII of the Periodic Table of the Elementsin order to impart hydrogenating/dehydrogenating properties to thecatalyst.

The catalysts for the above-mentioned catalytic hydrotreating which wereknown or have been developed have appeared to be suitable only forhydrocarbon fractions which are lighter than the heavier gas oils andthe hydrocarbon residues or residual oils. In particular the processingof residues and/or residual oils constitutes a growing problem. Formerlysuch products were sold as cheap residual fuel, but today they mustincreasingly be desulfurized as a result of a growing number ofregulations concerning air-pollution, in particular with respect topollution by sulfur-containing products such as sulfur dioxide However,the catalytic desulfurization of such heavier hydrocarbonfractions, inparticular of residues, constitutes a technological problem. Besidessaturated products, petroleum-residues have a high content ofpolyaromatics, resins and asphaltenes. In addition, such heavy hydrocaPbon fractions also contain so-called heavy metals, mainly vanadium andnickel. According tothe literature a vacuum residue of a crude petroleummay contain over 500 ppm. (parts per million) vanadium andover p.p.m.nickel, as metal. These metals are present in the heavy fraction mainlyin a complex form, viz. bound to the. asphaltenes. During the catalyticdesulfurization or hydrocracking of such asphaltenes-containing residuesthese-compounds deposit on the catalyst and degrade to carbon on thecatalyst surface, with simultaneous deposition of the heavy metals. Theactivity of the catalyst applied is lost fairly rapidly. Restoration ofthe catalyst activity byv simple carbon burn-off, as is common practicein petroleum refining, is not possible on account of the large amountsof interferingmetals accumulated on the catalyst surface.

In order to avoid the above difliculties it has been proposed to removethe asphaltenes by means of precipitation from the feed to bedesulfurized, prior. to catalytic desulfurizing. A drawback ofdeasphaltenizing is that material which is suitable for conversion intolower-hydrocarbons is removed; consequently, the yield decreasesaccordingly. On the other hand, no sulfur-free or practicallysulfur-free product can be obtained if the precipitated asphaltenes arecombined with the deasphaltenized and subsequently catalyticallydesulfurized oil, because the asphaltenes still contain and/or occludesulfur coman increase of the cost price of the final, desulfurizedproduct.

As far as is known, a chemical treatment method proposed in theliterature for freeing the heavy metal-loaded desulfurization catalystfrom these metals has not yet found application. The drawbacks of such atreatment are evident: in the first place it will make the regeneratedcatalyst very expensive; and in the second place the catalyticallyactive metals which are present on the catalyst, in particular thenickel, will be removed by the treatment.

SUMMARY OF THE INVENTION One of the objects of the present invention isto provide an active and stable hydrocarbon-conversion catalyst, inparticular in catalytic desulfurization and/or hydrocracking of residualoils. In this invention a porous silicaalumina based hydrocarbon-conversion catalyst is obtained by first preparing asilica/alumina hydrogel, preferably in the form of a cogel of aluminumhydroxide on silica hydrogel, which is shaped, if desired, and calcined.The xerogel thus obtained is neutralized with a nitrogen base andcontacted with an alkaline solution containing salts of catalyticallyactive hydrogenation metals. The impregnated xerogel is then subjectedto a controlled calcination whereby temperature is raised stepwise andthe required oxygen content is regulated to avoid sintering of theapplied metals. Catalysts thus prepared are active and stable in thehydrocracking and desulfurization of residual oils.

DETAILED DESCRIPTION (A) Hydrogel preparation A silica/ alumina hydrogelcan be prepared by any methd known in the art, such as: adding asilicate solution to an acidified aluminum salt solution; mixing asilicate solution and a solution of an alkali metal aluminate or analuminum salt and adjusting the pH of the combined solution to a valueof about 5-7 by adding either a base or an acid, depending on theconcentrations of the solutions used and on the mixing ratio; or cationexchanging a silicate solution in the acid form and adding an aluminuumsalt to the silica sol obtained. However, in order to obtain catalystswith highly porous silica/alumina carriers, which are specially suitablefor converting asphaltenes-containing hydrocarbon oils or fractions,preferably a hydrogel is prepared which is obtained in the form of acogel of aluminum hydroxide on silica hydrogel. The term cogel will beused for indicating a silica/ alumina composition obtained byprecipitating aluminum hydroxide on a silica hydrogel. Thus defined, acogel is not a coprecipitate, since in the preparation of acoprecipitate silicon hydroxide and aluminum hydroxide are precipitatedfrom the solution simultaneously or almost simultaneously. In thepreparation of a cogel one does not start directly from a silica sol,either.

According to a preferred embodiment of the process of the invention thehydrogel is obtained as a cogel by precipitating, in an aqueous medium,an aluminum hydroxide gel on a silica hydrogel by adding an aluminumcompound and an alkaline-reacting compound to a suspension of a silicahydrogel. For obtaining a silica hydrogel any method known in the artcan be applied, such as hydrolysis of esters of orthosilicates with theaid of mineral acids, or hydrolysis of silicon tetrachloride with coldmethanol in water. However, preferably alkali metals silicates areapplied in the preparation of the silica hydrogel. In a preferredprocess the silica/ alumina is obtained by first precipitating a silicahydrogel from an aqueous, silicate-ions-containing solution, such aswater-glass, by adding a mineral acid, subsequently adding an aluminumsalt to the solution and then precipitating the aluminum hydroxide gelby adding an alkaline-reacting compound.

As mineral acid any acid may be applied which is capable ofprecipitating a silica hydrogel from an aqueous,silicate-ions-containing solution. Th acid y b6 pp in the gaseous phase,as, for instance, in the case of "hydrogen chloride or carbon dioxide,or as an aqueous solution. In principle, however, the mineral acid willpreferably be the same as the anion of the aluminum salt to be added.Thus, when aluminum chloride is applied, preferably hydrochloric acidwill be used as mineral acid. Although, of course, this is not strictlynecessary. Those skilled in the art can easily add further examples tothe one given here.

In the cogel preparation preferably water-soluble aluminum salts, suchas aluminum sulfate, nitrate or chloride or mixtures thereof are appliedas aluminum compound. Preferably the aluminum salt is first added to theaqueous solution, either in the solid state or as a solution, prior tothe addition of the alkaline-reacting compound. Thus, the formation of ahomogeneous deposit of aluminum hydroxide gel on the silica hydrogel ispromoted.

As alkaline-reacting compound aqueous solutions of alkali metalhydroxides and/or alkaline earth metal hydroxides, such as sodium andpotassium hydroxide or calcium hydroxide, may be applied. Besides,suitable solutions of nitrogen bases may be used. It is preferable,however, to apply weakly alkaline solutions, in particular an aqueousammonia solution. Although the alkaline solution may be added in excess,the addition of the solution will usually be discontinued when nofurther precipitate is formed.

It is advisable to add the alkaline solution in parts, preferably whilestirring thoroughly. Additionin parts has the advantage that thealuminum hydroxide gel is more homogeneously distributed over the silicahydrogel already formed, and locally high concentrations of the gel areavoided. Also, intermediate ageing of the partially formed cogelpromotes the further uptake of the alumminum hydroxide gel. If ammoniais applied as alka1ine reacting compound can also be suitably introducedin the gaseous state.

For obtaining good results it is advisable to allow the silica hydrogelto age for a period of time, ranging from 5 minutes to some hours,before continuing the cogel preparation. Ageing may be effected at thetemperature which the solution had reached during the silica gelpreparation or a slightly elevated temperature. Ageing at temperaturesof ,20-75 (3., preferably of 24-40 C., for 5-1500 minutes has been foundto be very suitable. Ageing of the silica hydrogel occurs at a pH of thesolution between 4 and 7.

Usually, in the preparation of silica-alumina hydrogel dilute aqueoussolutions of silicates and of aluminum compounds are applied. Theconcentrations of these solutions may vary between wide limits and may,for instance, range from 1 to 35% w. However, preferably these solutionsare used in such proportions that in the hydrogel obtained thesilica-alumina weight ratio is between 95% silica-5% alumina and 40%silica-60% alumina. More specifically, this ratios is preferably betweensilica-10% alumina and 70% silica-alumina.

The mineral acids and/or alkaline-reacting compounds to be used are alsopreferably applied as dilute solutions. Generally, preference is givento acid solutions with a normality of 0.5-10 N; the concentration of thealkaline solution can also vary between these limits.

In the hydrogel preparation special preference is given to aluminumnitrate as the aluminum compound and to nitric acid as the mineral acid,because in the subsequent calcination, in which the hydrogel changesinto the xerogel, no impurities originating from the anion will remainin the xerogel.

After the formation of the hydrogel the precipitate formed is separatedfrom the liquid, for instance by means of filtration, decantation orotherwise. The precipitate separated is washed a few times with eitherion- -free water or a highly dilute solution of acid or ammonia, andsubsequently dried. Washing is preferably continued until no more alkalican be d tected in the washwater. The alkali metal or alkali earth metalcontent of the washed precipitate has then been reduced to below 0.5%wLUsually the cogel can more easily be freed from alkali by washing thanthe coprecipitate. When the coprecipitate is washed until the wash wateris alkali-free, the alkali content of this gel will generally be lowerthan 0.3, whereas in the same case the alkali content of the cogel willbe lower than 0.01% w. Drying is eifected at a temperature of at least100 C. Subsequently the hydrogel is calcined, preferably at atemperature in the range of from 450 to 600 C.for 1 to 16 hours. Goodresults were obtained by calcining at 500 C.'for at most 3 hours.

The catalyst preparation according to the process of the invention isespecially of importance when shaped catalyst particles are desired.Most, if not all, commercial catalyst applications call for a certainshape and size of the catalyst particles. For this reason, after thepreparation of the hydrogel this gel is usually formed into shapedparticles, such as extrudates, globules, pills, tablets, granules or thelike, prior to calcination. The techniques applied for this purpose,such as spray-drying, casting,.drying in rotary drums, etc., aregenerally known. The proposed neutralization step according to theinvention in particular has a favorable effect on the catalyticproperties of the final catalyst if shaping takes place after thehydrogel has been obtained, but before the application of thecatalytically active metals.

Before the hydrogel is formed into shaped particles it may, if desired,first be dried until it has a water content of about 70-90%. Such awater content especially facilitates shaping by means of extrusion andimproves the mechanical properties of the final particles. The hydrogelmay be dried to the air or at a slightly elevated temperature in, forinstance, a drying drum. After shaping, the shaped particles are driedfurther at temperatures in the range of from 100 to 200 C. and finallycalcined as indicated.

Instead of a cogel obtained according to the process described in theforegoing, a commercial cracking catalyst with a low alumina content canbe applied as cogel. Such cracking catalysts usually have an aluminacontent of about 13.6% w. and are also obtained as a cogel.

V (B) Neutralization 'After calcining, the xerogel obtained from thehydrogel is neutralized with a nitrogen base. For this purpose theXerogel is preferably first taken up in an aqueous solution of a salt ofa nitrogen base. The nitrogen base to be applied for the neutralizationneed not necessarily be the same as that from which the salt is derived,but preferably these nitrogen bases are the same. Suitable nitrogenbases-or salts derived therefrom-are ammonia, hydroxylamine, hydrazine,guanidine, the lower monoor polysubstituted N-alkyland alkanolamines,such as methylamine, diethylamine, monoethanolamine, triethanolamine,tetraalkylarnmonium hydroxide, pyridine or piperidine. Preference isgiven to the application of ammonia as the nitrogen base. Although, inprinciple, the salts derived from any acid can be applied, again thosesalts are preferred which are derived from acids which, in thesubsequent calcining of the xerogel, leave no residue. In view of thisconsideration, in particular the salts of nitrogen bases derived fromacids such as nitric acid and the lower monoor polybasic carboxylicacids, such as formic acid, acetic acid, oxalic acid, citric acid andthe like, are eligible. Preference is given to the ammonium andtetraalkylammonium salts of the acids mentioned.

With respect to the organic compounds the term lower is used in thisapplication to indicate those organic compounds which, in all, have atmost carbon atoms in their molecule.

The addition of the nitrogen base used for the neutralization iscontinued until the solution in which the xerogel has been taken up hasa constant'pH. Preferably-the neutralization is carried out in such away that this solution maintains a constant pH between 6.0 and 8.5 forat least 30 minutes. Since the solution in which the xerogel has beentaken up has to be allowed to stand for some time before it can beascertained whether the pH has remained constant, the neutralizationwill have to be carried out batchwise. Usually the neutralization willbe regarded as completed when the pH of the liquid remains at the valueof 7 for one hour.

The concentration of the solution of the nitrogen-base salt may varywithin wide limits. Good results have been obtained with salt solutionswith a molar concentration of 0.05 to 5, calculated on the nitrogenbase.

After the neutralization the xerogel is separated from the saltsolution, washed with ion-free water, and dried. Drying is preferablyeffected at elevated temperatures.

(C) Application of metals To the xerogel thus treated one or morecatalytically active metals are applied by one of the methods usuallyemployed for this purpose. Although any technique may may be applied,preference is given to impregnation. Impregnation may be effected by theusual methods. Catalytically active metals which are specially suited tothe purpose envisaged, are the metals belonging to Groups VB, VI-B,VII-B and VIII of the Periodic Table of the Elements, such as vanadium,molybdenum and tungsten, rhenium, the metals of the iron group and thoseof the platinum group. These metals are used separately or incombination with each other. Frequently applied combinations are thoseof tungsten and/or molybdenum with cobalt and/or nickel. With respect tothe conversion processes aimed at, very good results are obtained inparticular by applying the metals nickel and molybdenum as thecatalytically active metal components.

The metals of the platinum group are generally applied in a quantity of0.01 to 5 parts by weight of metal per parts by weight of xerogel. Theother metals may be applied in a quantity of 1 to 35 parts by weight ofmetal per 100 parts by weight of xerogel. Usually the total amount ofcatalytically active metal does not exceed 35 parts by weight. In thecase of combinations of metals of Group VI-B with metals of the irongroup (Group VIII) the Group VI-B metals are preferably applied in anamount of 5 to 30 parts by weight and the iron-group metals in an amountof 1 to 10 parts by weight.

. Very active catalysts are obtained when the Group VIII and GroupVI-"-B metals are applied in an atomic ratio between 0.1 and 1.0.Preferably these metals are applied to the xerogel in a quantity of atleast 100 milligramatoms of total metal load per 100 grams of carrier.

In a preferred embodiment of the invention the metals tungsten and/ ormolybdenum are applied to the neutralized Xerogel with the aid of analkaline-reacting impregnating solution. Preferably this solution has apH of at least 9, more specifically of from 10 to 13. This alkalinesolution may be an ammoniacal solution or an aqueous solution of anorganic nitrogen base, such as a lower alkylamine or alkanolamine,hydroxylamine, hydrazine or guanidine. Special preference is given tothe application of the lower alkanolamines, such as mono-, diandtriethanolamine.

If both tungsten and/ or molybdenum and a metal of the iron group areapplied as catalytically active metal components, the application of analkaline solution, in particular and aqueous alkanolamine solution, hasthe advantage that it permits these metals to be applied to the xerogelsimultaneously by means: of one solution.

The metals mentioned are preferably applied in the form of compoundswhich in the subsequent calcining leave no contaminating residue on orin the catalyst other than the metal or metal oxide concerned. Thereforepreference is given to salts of lower monoor polybasic carboxylic acids,in particular those with fewer than 8 carbon atoms, such as formic acid,acetic acid, oxalic acid, citric acid and the like. The correspondingamine complexes may also be applied. Those metals which may occur bothas a cation and an anion are preferably applied as their acids, such astungstic acid or molybdic acid or the ammonium salts thereof, such asammonium paratungstate or ammonium molybdate.

(D) Controlled calcination Although for the purpose in view the metalscould also be applied in the form of nitrates, the use of the lattergroup of compounds is not recommended because of the heat liberatedduring the calcination of the xerogel, as will be explained below.

After one or more catalytically active metals have been applied to theneutralized xerogel, the xerogol is calcined again. It has been foundthat this final calcining step has a greater influence on the propertiesof the final catalyst. During the calcining the ammonium hydroxideand/or other nitrogen bases present in or on the cogel will burn,consuming the oxygen needed for the calcining and developing aconsiderable amount of heat. Also the organic anion which may have beenused in applying the metals will contribute to the heat development.This liberated heat may cause local overheating, which has an adverseelfect on the final catalyst as regards structure and catalyticactivity. The heat liberated in the catalyst may cause sintering of theapplied metals, as a result of which the catalytically active materialwill be less finely and homogeneously distributed over the catalystsurface. In order to control these exothermic oxidation reactions thexerogel mentioned is preferably subjected to a controlled calcination inwhich the temperature is increased stepwise and in which the oxygencontent required for the calcination is regulated in dependence on thecatalyst temperature.

The above heat effect also occurs when ammonium hydroxide has been usedfor neutralizing the xerogel and no further organic compounds have beenapplied to or introduced into the xerogel during the application of thecatalytically active metals. Under the influence of the catalyst theammonia liberated during calcination oxidizes to form nitrogen andwater. This reaction is highly exothermic; the amount of heat liberatedis 75 Kcal./gram-molecule of ammonia.

The heat effects occurring in the calcination of the xerogel can bedemonstrated with the aid of differential thermal analysis (DTA). InFIGS. 1-4 the graphs are represented which have been obtained by thismethod during the calcination of two samples of catalysts preparedaccording to the invention. In all cases the reference compound is(1-Al20 FIG. 1 is a DTA record obtained by calcining neutralizedsilica-alumina xerogel impregnated with nickel and molybdenum in air bymeans of an ethanolamine solution. The nickel salt used was nickelnitrate.

FIG. 2 has been obtained by heating the same xerogel in nitrogen.

FIG. 3 has been obtained by calcination of anickelmolybdenum-containing, neutralized silica-alumina xerogel whichhas been prepared in the same way as the xerogel of FIG. 1, with theexception that nickel formate was the nickel salt used.

FIG. 4 has been obtained by heating the xerogel of FIG. 3 in nitrogen.

FIGS. 1 and 2 clearly show the strong heat effect which occurs whennitrates are used in applying the catalytically active metals, and showthat it is independent of the calcining medium. Therefore, it ispreferably to apply the catalytically active metals in the form of saltsderived from acids other than nitric acid or nitrous acid. Theapplication of, for instance, nickel formate as the nickel salt leads toa more active and more stable catalyst.

From FIGS. 3 and 4 it follows that exothermic heat effects of asilica-alumina impregnated with nickel formate can be kept well undercontrol during calcining by regulating the calcination medium.

The graphs discussed above show the importance of accurate control ofcalcining temperature. For this reason the neutralized, metal-loadedxerogel is preferably calcined at at least two different calcinationtemperatures, the first calcination temperature being in the range offrom 185 to 400 C., and the final calcination temperature being in therange of from 475 to 650 C., care being taken by regulating the amountof oxygen that, at the first and each subsequent calcinationtemperature, the temperature of the xerogel to be calcined is verylittle higher than the maximum permissible final calcinationtemperature. The material to be calcined is gradually heated to thefirst calcination temperature, which is the temperature at which thefirst heat effect occurs.

The magnitude of the heat effect is controlled by regulating the oxygensupply needed for the calcination. During the calcination thetemperature of the batch to be calcined is measured at regularintervals, and, as soon aS the temperature tends to increaseexcessively, the oxygen supply per unit time is reduced and/or the flowof the oxygen needed for the calcination is increased. The latter may beeffected in two ways. Either the flow rate of the oxygen-containing gasitself is kept constant and a second, inert, gas, such as nitrogen or arare gas, is passed through at a high or relatively high velocity, as aresult of which the oxygen content decreases and the material is cooledexternally, or, in certain cases, the flow rate of the oxygencontaininggas itself is increased. Although the latter measure will, in the firstinstance, lead to an increase of the oxygen supply per unit time, thehigher rate of flow will have a cooling effect on the material to becalcined.

Generally, it will be tried to keep the amount of heat removed duringthe calcination equal or practically equal to the amount of heatgenerated, by regulating the oxygen supply and/or increasing the oxygenflow.

When the temperature of the material to be calcined has become equal tothe first calcination temperature, and, on further increasing the oxygencontent, no further heat effects occur, the temperature is increased tothe second calcination temperature, i.e. the temperature at which thenext heat effect occurs. Thus, in a number of consecutive steps thematerial to be calcined is brought to the final calcination temperature,at which the metal compounds applied to the xerogel decompose and themetals are converted into their respective oxides.

As appears from the foregoing, the various calcination temperatures canbe simply determined by those skilled in the art, for instance, bydifferential thermal analysis or by means of the thermogravimetricbalance. The time during which the material to be calcined has to bekept at the first and each subsequent calcination temperature depends ona variety of factors, such as magnitude of the heat effect, size of thebatch to be calcined, layer thickness applied in the calcination, andthe like. The time of the final calcination temperature is preferablyfrom 1 to 5 hours.

Usually the application of two calcination temperatures will suffice, inwhich case the second will also be the final calcination temperature. Inthis case preferably a first calcination temperature between 270 and 370C. is applied and a second calcination temperature between 490 and 600C. In a preferred embodiment of the controlled calcination process thematerial to be calcined is first heated under a blanket of nitrogen oranother inert gas to a temperature which is 25 to C. below the firstcalcination temperature, after which an increasing amount of oxygen isadded to the inert gas, the temperature being gradually increasedfurther. When the first calcination temperature has been reached, and,on the oxygen content being further increased, the heat elfect starts,care is taken-by regulating the oxygen content as described above-thatthe temperature of the material to be calcined does not exceed 680 C.;preferably the latter temperature is. below 600 C. The oxygen contentapplied usually is in the range of from 0.5 to 2.5% w. When the heateffect has passed, at the first calcination temperature theoxygen-containing inert gas is gradually replaced by oxygen or by a gasmixture rich in oxygen, such as air, and subsequently the temperature isincreased to the second and final calcination temperature at which thexerogel is calcined for 1-5 hours. 1

The catalysts obtained according to the process of the invention arevery porous; at least 50% of the pore volume is accounted for by poreswith a diameter exceeding 75 A. They have a high initial activity, inparticular in the hydrodesulfurization of heavy feeds. This initialactivity k expressed in liters of feed per liter of catalyst per hour,is retained for a long time, in contrast with that of other, alreadyproposed catalysts, and hence the catalysts according to the inventionare very stable. The catalyst stability follows from the constant forthe decreasein activity, expressed as d (In k)/dt, which, in contrastwith that of the catalysts already proposed, is very small.

(E) Conversion feedstocks Although the catalysts according to theinvention can be applied for the conversion of hydrocarbons andhydrocarbon oils in general, they are more specifically suited to theconversion of heavier petroleum fractions such as hydrocarbon oils witha boiling range which substantially lies above 350 C. The catalystsmentioned are particularly suitable for the conversion of such oilswhich contain asphaltenes, a large amount of sulfur and/or a largeamount of heavy metals such as nickel, vanadium and iron. Examples ofsuch oils are crude petroleum itself or topped crude petroleum, long orshort residues, that is to say, the bottom products obtained in,respectively, atmospheric or vacuum distillation of crude petroleum(flashing), vacuum distillates, bottom products obtained in thermalcracking (visbreaking) of crude oils, catcracked cycle oils and also theso-called black oil and crude oils originating from shale, tar sand andthe like. If desired, the heavier oils or petroleum fractions mentionedcan first be deasphalt(en)ized, but this is certainly not necessary. Inparticular, the catalysts according to the invention are suitable forthe hydrocracking and/or hydrodesulfurization of such hydrocarbon oils.Furthermore these catalysts can be suitably applied for thehydrocracking of such heavier oils for the preparation of lubricatingoils. Specially eligible as the feed for such a conversion process aremixtures of flashed distillates and deasphalted residual oils.

(F) Process conditions The catalytic hydrotreatment in which thecatalysts according to the invention are applied is effected at elevatedtemperature and pressure. Suitable temperatures are in the range of from300 to 500 C., and suitable pressures in the range of from 35 to 350kg./cm. abs. The hydrodesulfurization of heavier petroleum fractionswhich contain asphaltenes besides a large amount of heavy metals(asphaltenes content 2% w., heavy metals content 25 p.p.m.w. in all,sulfur content 1.5% w.) is preferably effected under hydrocrackingconditions. Suitable conditions are a temperature in the range of from350 to 475 C. and a pressure of 100 to 250 kg./cm. abs. Preferablypressure and temperature are chosen such that at least 40% andpreferably 70 to 85% of the sulfur present in the feed is removed.

The space velocity of the feed varies from 0.2 to parts by volume ofhydrocarbon oil per volume of catalyst per hour; the hydrogen gas neededfor the conversion is supplied at a gas rate in the range of from 150 to5000 N1. hydrogen per kg. feed.

Y, The catalyst hydrotreatment is preferably carried out by using afluidized or moving catalyst bed in order to prevent the catalyst bedfrom becoming clogged, for instance as a result of the presence in theheavier oils of bituminous components such as asphaltenes. Various typesof fluidized or moving bed. may be applied, with or without liquidand/or gas recycling of the suspended catalyst.

The catalyst obtained according to the invention can be, applied inone-stage processes or as catalyst for the first stage of .atwo-stage ormulti-stage process. It is applied in the sulfided form and is thereforefirst sulfided in the usual way. The invention will be elucidatedfurther with the aid of the following examples.

EXAMPLE I I In this example the preparation of the catalyst according tothe invention, which is effected in four steps, is described in moredetail.

(a) Preparation of the silica-alumina cogel 2628 g. water-glass (silicacontent 26.5% w.) was made up with distilled water to 11,600 g., and thesolution obtained was heated to 40 C.,To the solution, which had a pH of11, 6 N HNO was slowly added until the pH was. exactly 6.0. In 30minutes 1045 ml. acid was added. The silica hydrogel formed. was agedfor 24 hours at 40 C}, with stirring. To the suspension of the agedsilica gel in 5 minutes 764 g. A1(NO -9H O, dissolved in water and madeup to 1224 g. was added while stirring..-ThelpH of the resulting liquidwas 2.8. The silica gel suspension was stirred for 10 minutes andsubsequently the pH was raised to 4.8 by means of a 25% solution ofammonia. After 10 minutes stirring the pH was raised once more, namelyto 5.5, by further addition of ammonia. The obtained hydrogel ofaluminum hydroxide on, silicon hydroxide was washed with distilledwater, until the filtrate was free from sodium ions (which was checkedwith the aid of magnesium uranyl acetate). The cogel then contained lessthan 0.01% w. sodium which cannot be removed by washing. The washedcogel was dried to the air (to a water content of and subsequentlyextruded into 1.5 mm. extrudates, which were dried at C. and thencalcined at 500 C. for 3 hours.

(b) Neutralizationof the xerogel Of the calcined cogel, which had asilica-alumina weight ratio of 87% w. Si0 :13% w. A1 0 412 g. wassuspended in 4120 =ml. of a molar NH NO solution. The pHof thesuspension was 4.5. By means of a concentrated ammonia solution (25%)the pH was raised to 7 and was maintained at this value by adding someammonia from time to time until the pH remained constant for 60 minutes(in all, about 25 ml. was added). The cogel thus treated was filteredoff, washed with distilled water, and dried atl00 C..

(c) Application er the metal Of the neutralized SiO /Al O xerogel 421 g.(394 g. dry matter) was impregnated with a solution containing nickeland molybdenum. This impregnating solution had been obtained bydissolving 116 g. ammonium heptamolybdate (54.3% Mo) and 25 g. nickelformate dihydrate separately in some water and subsequently com biningthe two solutions, while adding such an amount of monoethanolamine thatthe initially formed precipitate dissolved again. The total volume ofthe impregnating solution, which had a pH of 10.3, was 400 ml. Fifteenminutes after impregnation the xerogel was dried at 120 C.

(d) Calcination After impregnation the xerogel was calcined by means ofcontrolled calcination. For this purpose the extrudates were slowlyheated to 275 C. in a tubular oven equipped with a movable thermocouple,nitrogen being passed through at the rate of 40 l./h. Subsequently thetemperature of the oven was gradually increased to 350 C., oxygen beingadded to the nitrogen flow at such a rate that at 300 C. the oxygencontent was /2% v., at 325 C. 1% v., and at 350 C. 2% v. The temperatureof the tubular oven was then maintained at 350 C., the oxygen contentbeing increased to about 5% until it was observed by means of thethermocouple that the catalyst started and the oxidation of ammonia andother (organic) compounds commenced. By regulating the oxygen content,which was reduced to 2% v.and sometimes to a value below 2% v., it wasensured that the catalyst was burned off completely without allowing thetemperature of the catalyst to exceed 550 C. After the heat front hadpassed the whole catalyst bed the nitrogen flow was gradually replaced'by an air flow (40 l./h.). During the change-over to air, the catalysttemperature was carefully controlled, however, after the nitrogen flowhad been replaced completely, the temperature of the tubular oven wasincreased to 500 C. and maintained at this value for 3 hours.

The final catalyst (catalyst C) contained 2 parts by weight of nickeland 16 parts by weight of molybdenum per 100 parts by weight of carrier.-Its specific surface area was 292 mF/g. and its pore volume 0.71 ml./g.

EXAMPLE II The activity of catalyst C obtained as described in ExampleI, with respect to its desulfurizing and hydrogenating functions, wasdetermined in separate laboratory tests. As the feeds to be desulfurizedthiophene-containing toluene was used, and as the feed to behydrogenated benzene was applied. The activity of the catalyst wascompared with that of two other experimental catalysts of the samecomposition as catalyst C, except that one of these two catalysts(catalyst A) was obtained by directly impregnating the xerogel preparedaccording to Example 1(a), omitting the neutralizing step (b) and usingan aqueous solution of a nickel compound and a molybdenum compound,without using monoethanolamine; the other (catalyst B) was obtainedaccording to Example I, omitting the neutralization step (b), but usingmonoethanolamine. The results obtained, together with the conditionsapplied in the desulfurization and hydrogenation, are given in Table 1.The space velocity required to achieve a given level of desulfurizationor hydrogenation at constant operating conditions is used as a measureof activity, k

TABLE 1 Catalyst carrier: Slog-A120: cogel (13% w. AlzOt) Composition:2.0 p.b.w. Ni and 16.0 p.b.w. Mo per 100 p.b.w. xero(co)gel Theactivities show that both the application of an aqueous monoethanolaminesolution in applying the hydrogenating/dehydrogenating metals and theapplication of a neutralization treatment significantly improve thecatalyst activity.

EXAMPLE III In a model experiment the optimum load of the catalyst andthe optimum atomic ratio of Ni-Mo and of Ni-W were determined. For thispurpose, with the aid of a commercial silica-alumina (13% A1 0 a seriesof catalysts was prepared by means of impregnation with an aqueousmonoethanolamine solution. After calcination at 500 C. for 3 hours andsulfiding, the catalysts were tested for desulfurization activity forthiophene, as described in Example II. The results are given in Table 2.

TABLE 2 Desulfnriza- Atomic ratio Load in parts tion activity GroupVIII/ by weight per for thio- Applied Group VI B p.b.w. of phene, metalsmetal carrier mLmlfl-hr 0. 25 1.2 Ni/7.7 M0 0. 44 0. 25 2.4 Ni/l5.4 M00. 70 1. 00 2.95 Ni/4.8 Mo 0. 35 1.00 5.9 Ni/9.G Mo 0. 55 0. 25 l 2 Ni/ll.7 W 0. 23 O. 25 2 4 Ni/29.4 W 0. 44

Total load: 100 rug/at (Nos. 1, 3 and 5) or 200 nag/at (Nos. 2, 4 and 6)of Group VIII plus Group VI-B metal per 100 g. of carrier.

The above results show that preference should be given to aNi/Mo-containing catalyst with an atomic ratio of 0.25 and a total loadof 200 milligram-atoms of metal per 100 grams of carrier.

EXAMPLE IV This example was included to show the improved stability of acatalyst prepared by the method of the invention. Several catalysts werecompared for desulfurizing a long residue obtained from a Middle Eastcrude. The sulfur content of the residue was 4.1% w. Catalysts 1 and 2were obtained by impregnating an experimental alumina with a very largeaverage pore diameter with a solution in aqueous ethanolamine of,respectively, a nickel and a tungsten compound (catalyst 1), and acobalt and a molybdenum compound (catalyst 2). Catalyst 3 is acommerical catalyst based on zeolite Y. Catalyst 4 is an experimentalcatalyst obtained by treating a zeolite Y with an ammonium salt solutionuntil its sodium content is lower than 0.5/ w. Na O, and subsequentlyimpregnating it with an aqueous monoethanolamine solution of a nickeland a tungsten compound. Catalysts 5 and 6 are fluorided hydrocrackingcatalysts with a high fluorine content; catalyst 5 is a commercialcatalyst. Catalyst 7 is a commercially available desulfurizationcatalyst. Catalysts 8 and 9 were obtained by the process of theinvention. Catalyst 9 is the catalyst according to Example I; catalyst 8was obtained in the same way, with the exception of the nickel compoundused in the impregnation, which was nickel nitrate in this case. Theresults obtained and the desulfurization conditions applied are given inTable 3.

TABLE 3 Composition oft the liqltnddproduct, LHgg i ggsg; percen w. onee :2 Fraction, 375 0. H2 gastrate: Initial activity Constant for 500 N1, H2 activity Asphalper 1 feed desuliurdecrease tenes Average ization,--d(ln k), dt plus Catalyst (composition in pore Pressure, Temp, percent10 hr! Fraction. mal- Aro- Satparts by weight) diameter kgJcm. C. w.1.1- -hover 100 h.) 375 C. tones matics urates 1 Nllw/Alaol 180 200 40071. 1.2 2. 17.

2 c (l llfifl 170 8 9 16 9 36 9 28.3 0 r a 200 400 71 1.2 4.9 16.5 1 3P%6/q.gm) 8 7 v 6 36 9 30 1 zeoi e l 5 420 8 19.4

4 W/Ni/zeolite Y 8 150 400 15 5 W/Ni/F/SiOz-AlzO: 60 150 420 69 1.1 4.1

6 W/Ni/F/AlzOz 90 150 420 71 1.2 4.8

7 o/Mo/AlaOs 80 150 400 82 2.2 4.0

8 Nl/M10/?iO2A12Oa cogel 90 150 400 75 1.5 2.3

e Ni/Mo/SiOi-AlzOa cogel Feed I Contains 2.0% w. N520. b Contains 0.3%w. N820- s Nickel applied as Ni (N 0:): instead of as nickel formate.

The data of this table show that the commercial catalyst 7 has thehighest initial activity, but the stability of this catalyst is muchlower than that of the silica/aluminacogel-based catalyst according tothe invention, as appears from the constant for the activity decreaseover the first hundred run hours, which is 4.0 to 2.3/ 0.5,respectively. The special influence of the application of nickel formateon the activity and stability of the catalysts becomes evident when thedata for catalysts 8 and 9 are compared.

EXAMPLE V The hydrocracking activity of the catalyst of Example I wascompared with that of two commercially available catalysts in theone-stage hydrocracking of a deasphialted long residue. I

The feed had been obtained in the following way. A long residue from aMiddle East crude oil was flashed at 390 C. and 60 mm. Hg. Thedistillate obtained contained 2.8% w. sulfur (S) and no vanadium (V).The remaining short residue, which contained 5.4% S and 100 p.p.m.w. V,was deasphalted in two stages. For this purpose it was treated withpentane at C. at the ratio of 5 parts by volume of pentane per volume ofshort residue. The precipitated C -asphaltenes were separated and theextract was heated to 185 C. at a pressure of 30 atm.

An oil which, under these conditions, was not soluble in pentaneseparated; this oil was removed. After the pressure had been decreased,the pentane was removed from the extract by distillation, and adeasphalted residual oil was obtained which contained 4.4% W. S and 28p.p.m.w. V. The whole of the latter oil was mixed with the earlierobtained flashed distillate. Thus, a desaphalted long residue containing3.5% w. S. and 11 p.p.m.w. was obtained in a yield of 80% on the orginallong residue.

The deasphalted long residue was cracked at a temperature of 400 C. anda pressure of 100 kg./cm. The space velocity applied was 0.5 liter offeed per liter of catalyst per hour, and the hydrogen/feed ratio was2000 N1. per liter of feed.

One of the above-mentioned two commercially available catalysts had asilica-alumina carrier and tungsten and nickel as the active metalcomponents, its composition being: 8 parts by weight of Ni and 26 partsby weight of W per 100 parts by weight of carrier (79% SiO -21% A1 0 andthe other had an alumina carrier and molybdenum and nickel as the activemetal components, its composition being: 3.1 parts by weight of Ni and11.7 parts by weight of M0 per 100 parts by weight of A1 0 Thehydrocracking products were fractionated, and some of the propertieswere determined. The results are given in Table 4.

TABLE 4 Catalyst 0 Commercial Commercial Mo/Ni on W/Ni on Mo/Ni onSlog-A: SiOrAlzOa AlzOs (Example I) Catalyst (26/8/100) (11.7/3.1/100)(16/2/100) Composition of liquid product. percent w.:

Fraction 80 C 1. 4 Fraction 80-180 C 7. 6 4. 3 11. 9 Fraetion-180250 C.7.3 5. 3 11. 3 Fraction 250-375 C4.-. 31. 4 30. 0 36. 7 Fraction 375 C53. 7 50.0 40. 1 Properties: .1

Fraction 801180 0.: 3 Aromatics, percent w i 26. 3 20. 8

Fraction 180-250 0.:

Aromatics, percent 7 v Y 37. 5 36. 5 28. 8 Smoke point, mm 1 v 13. 2 13.2 1 15. 5 Fraction 250375 0.:

Cloud point, C -1 0 ii Diesel index 47 48 57 The catalyst accordingtothe invention is very suitable for converting heavy feed into naphthaand middle distillates with a high conversion. The above results showthat hardly any light products (fraction 80 C.) are formed, and thatvthe gas oil obtained (fraction 250-375 C.) has a high diesel index. Thefraction 375 C. can be used for luboil manufacture, and also theremaining fractions can be used as feed for other conversion processes.

EXAMPLE 'VI A long residue of a crude oil originating from the MiddleEast was hydrodesulfurized with the aid of the catalyst obtainedaccording to Example I, under different conditions as regards spacevelocity and temperature. The catalyst was used in the form of 1.5 mm.extrudates; it had previously been sulfided by :means of a mixture ofhydrogen and hydrogen sulfide, using a cold-start-up procedure. Thehighest temperature applied in sulfiding wasaso" 'C. v

The pressure used in thevarious experiments was kg.'/crh. and thehydrogen gas rate was 500 N1. per kg. feed. The results obtained and theanalytical data of the total liquid product are given in Table 5.

TABLE 5 Conditions:

Space velocity, LI -h. 0.75 0. 75 1. Temperature, C 390 400 400 Feed Produet Product Product Composition, percent w.:

Fraction 375 C 12. 3 24. 4 34. 1 30. 1 Asphaltenes. 4. 2 2. 6 2. 4 2. 2Resins 22. 5 14. 5 10. 3 11. 2 Aromatics 38. 2 28. 8 23. 0 25. 8saturates 22. 8 29. 7 30. 2 30. 6

Total 100. 0 100. 0 100. 0 99. 9

Sulfur, percent w 4.05 l. 23 0. 76 O. 80 Nickel, p.p.m.w 16 6 4Vanadium, p.p.m.w 49 17 12 From the above data, it is obvious that,under the conditions applied, the catalyst according to the inventionalso converts bituminous oil components, namely, asphaltenes and resins.Of the fractions boiling above 375 C. the heavy-metal content hasdecreased considerably, and also the sulfur content has decreased by atleast 70%.

EXAMPLE VII In a pilot plant a long residue originating from a Caribbeancrude oil was hydrodesulfurized over the catalyst of Example I. Thecatalyst was applied in the form of particles with a particle size of0.4-1.0 mm. (35-18 mesh). The feed had a sulfur content of 2.1% w. and ametal content of 29 p.p.m.w. Ni and 205 p.p.m.w. V. After sulfiding ofthe catalyst, stable operation was reached after 400 kg. feed per kg.catalyst had passed over the catalyst bed at a pressure of 150 kg./Cm. atemperature of 420 C., a space velocity of 2.2 liters of feed per literof catalyst per hour, and a hydrogen-gas feed rate of 500 Nl. per literof feed. The sulfur content of the product obtained then had beenreduced by more than 40% w.

We claim as our invention:

1. A hydrocracking process which comprises contacting a residual oilwith hydrogen under hyrocracking conditions with a catalyst comprising ahydrogenation metal component on a porous silica-alumina support, saidcatalyst being prepared by the method which comprises:

(a) calcining a silica-alumina cogel and then neutralizing the calcinedsupport with a nitrogen base;

(b) depositing a hydrogenation metal component on said neutralizedsupport by contacting it with an alkaline solution containing a salt ofsaid catalytically active metal component;

(c) calcining said salt-containing neutralized support in anoxygen-containing gas at a temperature in the range of about 185-400 C.,the oxygen content of said gas and calcining time being regulated toavoid sintering the hydrogenation metal component; and

(d) finally calcining said salt-containing neutralized support in anoxygen-containing gas at a temperature in the range of about 475-650 C.for at least about 1 hour.

2. The process of claim 1 wherein said silica-alumina support containsfrom 40-95% wt. silica.

3. The process of claim 2 wherein the silica-alumina support is preparedas a cogel of aluminum hydroxide on a silica hydrogel.

4. The process of claim 1 wherein the nitrogen base used to neutralizethe calcined support is ammonium hydroxide.

5. The process of claim 1 wherein said catalytically active metalcomponent is selected from the group consisting of cobalt, nickel,molybdenum and tungsten.

6. The process of claim 5 wherein the catalytically active metalscomponent includes both nickel and molybdenum and the nickel is appliedto the support from an alkaline nickel formate solution.

7. The process of claim 1 wherein the salt-containing neutralizedsupport of step (b) is first heated under a blanket of inert gas to atemperature which is 25 to C. below the first calcination temperature ofstep (c), after which from 0.5 to 2.5% v. oxygen is added and thetemperature is gradually increased to said first calcination temperaturein the range of 185-400 C.

8. A hydrodesulfurization process which comprises contacting a residualoil with hydrogen under hydrodesulfurization conditions with a catalystcomprising a hydrogenation metal component on a porous silica-aluminasupport, said catalyst being prepared by the method which comprises:

(a) calcining a silica-alumina cogel and then neutralizing the calcinedsupport with a nitrogen base;

(b) depositing a hydrogenation metal component on said neutralizedsupport by contacting it with an alkaline solution containing a salt ofsaid catalytically active metal component;

(c) calcining said salt-containing neutralized support in anoxygen-containing gas at a temperature in the range of about 185-400 C.,the oxygen content of said gas and calcining time being regulated toavoid sintering the hydrogenation metal component; and

(d) finally calcining said salt-containing neutralized support in anoxygen-containing gas at a temperature in the range of 475-650 C. for atleast about 1 hour.

9. The process of claim 8 wherein said silica-alumina support containsfrom 40-95% Wt. silica and is prepared as a cogel of aluminum hydroxideon a silica hydrogel.

10. The process of claim 8 wherein the nitrogen base used to neutralizethe calcined support is ammonium hydroxide and said catalytically activemetal component is selected from the group consisting of cobalt, nickel,molybdenum and tungsten.

11. The process of claim 10 wherein the catalytically active metalcomponent includes both nickel and molybdenum and the nickel is appliedto the support from an alkaline nickel formate solution.

12. The process of claim 8 wherein the salt-containing neutralizedsupport of step (b) is first heated under a blanket of inert gas to atemperature which is 25 to 100 C. below said first calcinationtemperature of step (c), after which from 0.5 to 2.5% v. oxygen is addedand the temperature is gradually increased to said first calcinationtemperature in the range of 185-400 C.

13. The process of claim 8 wherein the hydrocarbon is anasphaltene-containing residual oil having a boiling range substantiallyabove 350 C., and the silica-alumina supported catalyst includes l-l0parts by weight of nickel and 5-30 parts by weight of molybdenum, saidmetals being in the sulfide form.

14. The process of claim 13 wherein the sulfur content of the residualoil is reduced by at least 50% at a temperature in the range from 300 to500 C., a pressure in the range of from 35-350 kg./cm. a space velocityof 0.2 to 10 parts by volume of oil per volume of catalyst per hour anda hydrogen/oil ratio of to 5,000 Nl. per kilogram of feed.

References Cited UNITED STATES PATENTS 3,285,860 11/1966 Richardson 208216 3,471,399 10/1969 OHara 208216 3,016,347 1/1962 OHara 208-216DELB'ERT E. GANTZ, Primary Examiner G. I. CRASANAKIS, Assistant ExaminerUS. Cl. X.R. 208-216, 217

